Cold expansion tool for expanding a bore through a part

ABSTRACT

An expansion tool comprises a tool body for manipulating the tool, a drive module for driving the rotation of a cylindrical needle cage in the bore, the cylindrical needle cage having an axis of revolution about which the needle cage is configured to start to rotate in the bore, the needle cage comprising needles configured to move radially away from the axis of revolution so as to work-harden the bore as the needle cage is rotationally driven by the drive module. The expansion tool also comprises a rod having a burnisher configured to move the needles of the needle cage radially as the burnisher passes through the needle cage as a result of the translational movement of the rod. The rotation of the needle cage allows the entire internal surface of the bore to be work-hardened.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 1854295 filed on May 23, 2018, the entire disclosures of which are incorporated herein by way of reference.

FIELD OF THE INVENTION

The present invention relates to a cold expansion tool for expanding a bore formed through a part.

BACKGROUND OF THE INVENTION

The cold expansion of a bore is usually employed to work-harden the material of a part on the surface of a bore formed through the part. Work-hardening makes it possible to alter the mechanical properties of the material of the part in the region of the bore. It makes it possible to delay the onset or propagation of cracks caused by the fatigue of the material.

At the present time, cold expansion is performed using a burnisher and a split sleeve. The split sleeve is placed inside the bore. The burnisher is then forcibly passed through the inside of the sleeve. Because the outside diameter of the burnisher is greater than the inside diameter of the split sleeve, the forcible passage of the burnisher through the split sleeve causes the sleeve, and the bore, to expand.

The use of a split sleeve leads to disadvantages. In particular, it may leave part of the internal surface of the bore not work-hardened in the region of the split of the split sleeve and may lead to poor distribution of the residual stresses caused by the expansion. In addition, a method employing a split sleeve places numerous restrictions which are down to the material and to the direction of the fiber formation of the part that is to be expanded.

SUMMARY OF THE INVENTION

It is an object of the present invention to alleviate these disadvantages by proposing a tool that allows cold expansion.

To this end, the invention relates to a cold expansion tool for expanding a bore through a part.

According to the invention, the cold expansion tool comprises:

a tool body configured for manipulating the cold expansion tool;

a first drive module configured for driving the rotation of a cylindrical needle cage in the bore, the cylindrical needle cage having a first axis of revolution about which the needle cage is configured to start to rotate in the bore, the needle cage comprising needles configured to move radially away from the first axis of revolution so as to work-harden the bore as the needle cage is rotationally driven by the first drive module;

a rod having a second axis of revolution, the rod being configured to be inserted in the needle cage, the rod having a first end equipped with a burnisher configured to move the needles of the needle cage radially as the burnisher passes through the needle cage, the rod being configured to enter the tool body translationally along the second axis of revolution parallel to the first axis of revolution so as to cause the burnisher to pass through the needle cage;

a second drive module configured to drive the rod translationally along the second axis of revolution so that the burnisher passes all the way through the needle cage held in the bore.

Thus, the first drive module may drive the rotation of a needle cage introduced into the bore. The rotation of the needle cage in the bore allows the entire internal surface of the bore to be treated by work-hardening without leaving part of the internal surface untreated thanks to the burnisher which passes through the needle cage moving the needles radially out away from the first axis of revolution.

According to a first alternative form, the rod comprises:

a second end having a screw thread and

a portion comprising first splines,

the tool body comprising an opening having a tapped thread, the screw thread of the second end of the rod being configured to engage with the tapped thread of the opening of the tool body,

and the second drive module comprising a first gearwheel, a second gearwheel and a first motor fixed to the tool body, the first motor being configured to generate a first driving torque, the first gearwheel being configured to transmit the first driving torque to the second gearwheel, the second gearwheel comprising a hub having second splines, the second splines being configured to engage with the first splines of the portion of rod so as to drive the rotation of the rod about the second axis of revolution, the rotation of the rod causing the translational movement of the rod as a result of the engagement of the screw thread of the second end of the rod with the tapped thread of the opening of the tool body.

According to a second alternative form, the tool comprises a third drive module configured to drive the rotation of the rod about the second axis of revolution.

Furthermore, the first drive module comprises the second drive module, the burnisher being configured to drive the rotation of the needle cage using friction as the burnisher passes through the needle cage.

In addition, the first drive module comprises the third drive module, the burnisher being configured to drive the rotation of the needle cage using friction as the burnisher passes through the needle cage.

Furthermore, the first drive module comprises:

a cylinder comprising a first connection device,

a third gearwheel,

a fourth gearwheel coaxial with and secured to the cylinder, and

a second motor fixed to the tool body and configured to generate a second driving torque,

the cylinder having a third axis of revolution coincident with the first axis of revolution,

the third gearwheel being configured to transmit the second driving torque to the fourth gearwheel,

the fourth gearwheel being configured to drive the rotation of the cylinder about the third axis of revolution when the third gearwheel is transmitting the second driving torque to the fourth gearwheel,

the first connection device being configured to engage with a second connection device of the needle cage so that rotation of the cylinder about the third axis of revolution can drive the rotation of the needle cage about the first axis of revolution.

The invention also relates to an assembly configured to perform cold expansion of a bore through a part.

According to the invention, the assembly comprises:

a cold expansion tool for expanding a bore through a part as described hereinabove, and

a cylindrical needle cage having a first axis of revolution about which the needle cage is configured to begin to rotate in the bore, the needle cage comprising needles having longitudinal axes which are arranged to be parallel to the first axis of revolution, the needles being configured to move radially away from the first axis of revolution so as to work-harden the bore while the needle cage is rotationally driven by the first drive module.

The invention also relates to a method for using an assembly configured to perform cold expansion of a bore through a part as described hereinabove,

characterized in that it comprises the following steps:

a step of placing the needle cage in the bore,

a step of holding the needle cage in the bore,

a step of rotationally driving the needle cage in the bore using the first drive module,

a step of causing the rod a translational movement along the second axis of revolution, this being implemented by the second drive module, consisting in driving the translational movement of the rod along the second axis of revolution so that the burnisher passes all the way through the needle cage held in the bore.

Furthermore, the method comprises:

a step of sliding the needle cage onto the rod, the sliding step preceding the step of placing the needle cage in the bore.

In addition, the method further comprises a step of setting the rod in rotation about the second axis of revolution, this step being implemented by the second drive module, the step of starting rotation being concomitant with the step of starting translation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with its features and advantages, will become more clearly evident from reading the description given with reference to the attached drawings in which:

FIG. 1 is a profile view of one embodiment of the cold expansion tool equipped with a needle cage before the burnisher passes through the needle cage,

FIG. 2 depicts a profile view of the embodiment of FIG. 1 of the cold expansion tool equipped with a needle cage as the burnisher passes through the needle cage,

FIG. 3 depicts a profile view of the embodiment of FIG. 1 of the cold expansion tool equipped with a needle cage after the burnisher has passed through the needle cage,

FIG. 4 is a schematic view of the method for using the assembly comprising the cold expansion tool and the needle cage,

FIG. 5 depicts a perspective view of a needle cage,

FIG. 6 depicts a view of a needle cage in the direction of the line of revolution of the needle cage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the cold expansion tool 1 is depicted in FIGS. 1 to 3.

The cold expansion tool 1 allows expansion of a (circular) bore 2 through a part 3.

The part 3 may be a plate. The part 3 may comprise several parts stacked together. Some of these parts may be made of composite material.

The cold expansion tool 1 comprises a tool body 4.

As depicted in FIGS. 1 to 3, the tool body 4 may be in the shape of a gun comprising a holding device 31 that allows a user to manipulate and/or to use the cold expansion tool 1.

The cold expansion tool 1 also comprises a first drive module 23 configured to drive the rotation of a cylindrical needle cage 5 introduced into the bore 2.

The cold expansion tool 1 and the needle cage 5 then form an assembly 32 configured to perform cold expansion of a bore 2.

FIGS. 5 and 6 depict examples of needle cages 5 capable of being driven by the first drive module 23.

In these FIGS. 5 and 6, the cylindrical needle cage 5 has an axis of revolution 6 about which the needle cage 5 is configured to begin to rotate in the bore 2. The needle cage 5 comprising needles 7 having longitudinal axes 8 which are configured to be parallel to the axis of revolution 6. The needles 7 are configured to move radially away from the axis of revolution 6 so as to work-harden the surface of the bore 2 while the needle cage 5 is being rotationally driven by the first drive module 23. In FIG. 5, the double arrow indicated by the reference 9 represents the possible movements of a needle 7 of a needle cage 5. In order to work-harden the surface of the bore 2, the movement corresponds to that part of the double arrow that indicates a direction away from the axis of revolution 6.

Advantageously, the first drive module 23 has a connection interface 10 allowing the needle cage 5 to be kept in the bore 2 as the needle cage 5 is rotationally driven by the first drive module 23.

According to one embodiment of the cold expansion tool 1 depicted in FIGS. 1 to 3, the cold expansion tool 1 comprises a rod 11 having an axis of revolution 12 and a second drive module 15.

The rod 11 is configured to be inserted into the needle cage 5. The rod 11 having an end 13 fitted with a burnisher 14. The burnisher 14 is configured to move the needles 7 of the needle cage 5 radially as the burnisher 14 passes through the needle cage 5 (FIG. 2). The rod 11 is therefore configured to enter the tool body 4 translationally along the axis of revolution 12 parallel to the axis of revolution 6 so that the burnisher 14 can pass through the needle cage 5. FIG. 1 depicts the burnisher 14 before it passes through the needle cage 5. FIG. 3 depicts the burnisher 14 after it has passed through the needle cage 5.

For example, the burnisher 14 has a cylindrical shape, its ends ending in a hemispherical or conical shape. Advantageously, the diameter of the cylinder that forms the burnisher 14 is substantially less than or equal to the diameter of the bore 2 and substantially greater than the inside diameter of the needle cage 5 when the needles 7 are retracted close to the axis of revolution 6. The diameter of the needle cage 5 when the needles are moved away from the axis of revolution 6 is substantially greater than the diameter of the bore 2.

The second drive module 15 is configured to drive the rod 11 translationally along the axis of revolution 12 so that the burnisher 14 passes all the way through the needle cage 5 held in the bore 2.

According to a first alternative form of the first embodiment of the cold expansion tool 1, which first alternative form is depicted in FIGS. 1 to 3, the rod 11 comprises:

and end 16 having a screw thread 17 and

a portion 18 comprising first splines.

In this first alternative form, the tool body 4 comprises an opening 19 having a tapped thread. The screw thread 17 of the end 16 of the rod 11 is configured to engage with the tapped thread of the opening 19 of the tool body 4.

In addition, the second drive module 15 comprises a gearwheel 20, a gearwheel 21 and a motor 22 fixed to the tool body 4. The motor 22 is configured to generate a first driving torque.

The gearwheel 20 is configured to transmit the first driving torque to the gearwheel 21. The second gearwheel 21 comprises a hub having second splines (not depicted). The second splines are configured to engage with the first splines of the portion 18 of the rod 11 so as to drive the rotation of the rod 11 about the axis of revolution 12 while at the same time allowing the rod 11 a translational movement along the axis of revolution 12. The rotation of the rod 11 causes the translational movement of the rod 11 because of the interaction between the screw thread 17 at the end 16 of the rod 11 and the tapped thread of the opening 19 of the tool body 4. The first splines of the portion 18 are long enough to allow permanent connection between the first and second splines despite the translational movement of the rod 11 with respect to the second gearwheel 21. For example, the length of the second splines is greater than or equal to a maximum distance that the rod 11 covers in its translational movement.

In this first alternative form, the second drive module 15 provides the translational and rotational movements of the rod 11.

According to a non-depicted second alternative form of the cold expansion tool 1, the cold expansion tool 1 comprises a third drive module configured to drive the rotation of the rod 11 about the axis of revolution 12. Thus, the rotation of the rod 11 about the axis of revolution 12 is independent of the translational movement of the rod along the axis of revolution 12. In this second alternative form, the second drive module may be an actuating cylinder and the third drive module may be a motor generating driving torque.

According to a first embodiment of the first drive module not depicted, the first drive module comprises the second drive module 15. The burnisher 14 may be driven by the rotation of the rod 11 about the axis of revolution 12, the rod being driven rotationally and translationally by the second drive module 15. The burnisher 14 is then configured to drive the rotation of the needle cage 5 by friction as the burnisher 14 passes through the needle cage 5.

According to a second embodiment of the first drive module not depicted, the first drive module comprises the third drive module. The burnisher 14 may be driven by the rotation of the rod 11 about the axis of revolution 12, the rotation of the rod being driven by the third drive module. As with the first embodiment of the first drive module, the burnisher 14 is configured to drive the rotation of the needle cage 5 by friction as the burnisher 14 passes through the needle cage 5.

According to a third embodiment of the first drive module depicted in

FIGS. 1 to 3, the first drive module 23 comprises:

a cylinder 24 comprising a connection device 25,

a gearwheel 26,

a gearwheel 27 coaxial with and secured to the cylinder 24, and

a motor 28 fixed to the tool body 4 and configured to generate a second driving torque.

In this third embodiment of the first drive module, the cylinder 24 has an axis of revolution 29 coincident with the axis of revolution 6. The gearwheel 26 being configured to transmit the second driving torque to the gearwheel 27. The gearwheel 27 is configured to drive the rotation of the cylinder 24 about the axis of revolution 29 when the gearwheel 26 is transmitting the second driving torque to the gearwheel 27. The connection device 25 is configured to engage with a connecting device 30 of the needle cage 5 so that rotation of the cylinder 24 about the axis of revolution 29 can drive rotation of the needle cage 5 about the axis of revolution 6.

The assembly configured to perform cold expansion comprising the cold expansion tool 1 and the needle cage 5 can be used according to the following method of use (FIG. 4).

The method of use comprises the following steps:

a step E2 of placing the needle cage 5 in the bore 2,

a step E3 of holding the needle cage 5 in the bore 2,

a step E4 of rotationally driving the needle cage 5 in the bore 2 using the first drive module 23,

a step E51 of causing the rod 11 a translational movement along the axis of revolution 12, this being implemented by the second drive module 15, consisting in driving the translational movement of the rod 11 along the second axis of revolution 12 so that the burnisher 14 passes all the way through the needle cage 5 held in the bore 2. This step E51 follows the step E4 of driving the rotation of the needle cage 5.

According to the embodiment of the expansion tool 1 depicted in FIGS. 1 to 3, the method of use may further comprise:

a step El of sliding the needle cage 5 onto the rod 11. This step El precedes the step E2 of placing the needle cage 5 in the bore 2.

The method of use may also comprise a step E52 of causing the rod 11 to rotate about the axis of revolution 12, the step E52 of causing rotation being concomitant with the step E51 of causing translational movement.

While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority. 

1. A cold expansion tool for expanding a bore through a part, comprising: a tool body configured to manipulate the cold expansion tool; a first drive module configured to drive a rotation of a cylindrical needle cage in the bore, the cylindrical needle cage having a first axis of revolution about which the needle cage rotates in the bore, the needle cage comprising needles configured to move radially away from the first axis of revolution so as to work-harden the bore as the needle cage is rotationally driven by the first drive module; a rod having a second axis of revolution, the rod configured to be inserted in the needle cage, the rod having a first end equipped with a burnisher configured to move the needles of the needle cage radially as the burnisher passes through the needle cage, the rod being configured to enter the tool body translationally along the second axis of revolution parallel to the first axis of revolution to cause the burnisher to pass through the needle cage; a second drive module configured to drive the rod translationally along the second axis of revolution so that the burnisher passes all the way through the needle cage held in the bore.
 2. The tool according to claim 1, wherein the rod comprises: a second end having a screw thread and a portion comprising first splines, wherein the tool body comprises an opening having a tapped thread, the screw thread of the second end of the rod being configured to engage with the tapped thread of the opening of the tool body, and wherein the second drive module comprises a first gearwheel, a second gearwheel and a first motor fixed to the tool body, the first motor being configured to generate a first driving torque, the first gearwheel being configured to transmit the first driving torque to the second gearwheel, the second gearwheel comprising a hub having second splines, the second splines being configured to engage with the first splines of the portion of rod so as to drive a rotation of the rod about the second axis of revolution, the rotation of the rod causing a translational movement of the rod as a result of an engagement of the screw thread of the second end of the rod with the tapped thread of the opening of the tool body.
 3. The tool according to claim 2, further comprising a third drive module configured to drive the rotation of the rod about the second axis of revolution.
 4. The tool according to claim 2, wherein the first drive module comprises the second drive module, the burnisher being configured to drive the rotation of the needle cage using friction as the burnisher passes through the needle cage.
 5. The tool according to claim 3, wherein the first drive module comprises the third drive module, the burnisher being configured to drive the rotation of the needle cage using friction as the burnisher passes through the needle cage.
 6. The tool according to claim 1, wherein the first drive module comprises: a cylinder comprising a first connection device, a third gearwheel, a fourth gearwheel coaxial with and secured to the cylinder, and a second motor fixed to the tool body and configured to generate a second driving torque, the cylinder having a third axis of revolution coincident with the first axis of revolution, the third gearwheel being configured to transmit the second driving torque to the fourth gearwheel, the fourth gearwheel being configured to drive a rotation of the cylinder about the third axis of revolution when the third gearwheel is transmitting the second driving torque to the fourth gearwheel, the first connection device being configured to engage with a second connection device of the needle cage so that rotation of the cylinder about the third axis of revolution can drive the rotation of the needle cage about the first axis of revolution.
 7. An assembly configured to perform cold expansion of a bore through a part, comprising: a cold expansion tool configured to expand a bore through a part according to claim 1, and a cylindrical needle cage having a first axis of revolution about which the needle cage is configured to begin to rotate in the bore, the needle cage comprising needles having longitudinal axes which are arranged parallel to the first axis of revolution, the needles being configured to move radially away from the first axis of revolution to work-harden the bore while the needle cage is rotationally driven by the first drive module.
 8. A method for using the assembly configured to perform cold expansion of a bore through a part according to claim 7, comprising the following steps: placing the needle cage in the bore, holding the needle cage in the bore, rotationally driving the needle cage in the bore using the first drive module, causing the rod to translationally move along the second axis of revolution, this being implemented by the second drive module, comprising driving a translational movement of the rod along the second axis of revolution so that the burnisher passes all the way through the needle cage held in the bore.
 9. The method according to claim 8, further comprising: sliding the needle cage onto the rod, the sliding step preceding the step of placing the needle cage in the bore.
 10. The method according to claim 8, further comprising setting the rod in rotation about the second axis of revolution, this step being implemented by the second drive module, the step of starting rotation being concomitant with the step of starting translation. 